456 



The exceptional liver of the pig, with its distinct lobules, seems 

 to bear in structural peculiarity the same relation to the livers of 

 other animals, as the much-divided kidney of the porpoise bears to 

 the more solid organ of most mammalian animals. 



In a. physiological sense the livers of all vertebrate animals may 

 be said to be composed of lobules ; but in a strictly anatomical sense 

 this term can only be used with reference to the liver of the pig, and, 

 according to Miiller, that of the polar bear. The vessels and duct, 

 at their entrance into the liver, are invested with much areolar 

 tissue, which is continued for a considerable distance along the 

 portal canals; but it gradually ceases as the vessels become smaller, 

 and, with the exception of the liver of the pig above referred to, the 

 lobules are not separated from each other by any areolar tissue, or 

 by any fibrous tissue whatever, neither is any prolonged into their 

 substance. Hence the investment of areolar tissue round the vessels 

 in the portal canals of the liver seems to present no peculiar charac- 

 ters in its distribution. It must be borne in mind, that in the exa- 

 mination of uninjected specimens the small vessels and ducts are 

 liable to be much stretched and torn in manipulation, and, in conse- 

 quence, a striated appearance is produced which closely resembles 

 fibrous tissue. 



Method of preparing specimens. In order to demonstrate the 

 arrangement of the ducts described by the author, it is absolutely 

 necessary to harden the liver previously. This hardening may be 

 effected by soaking a portion of the liver for some time in strong 

 syrup, or in alcohol, and afterwards rendering the section trans- 

 parent by soda. The mixture of alcohol and acetic acid recom- 

 mended by Mr. L. Clarke in his investigations upon the spinal cord, 

 has also been employed, as well as many other solutions which are 

 not described. The fluid to which the author gives the preference 

 is alcohol, to which a few drops of solution of soda have been 

 added. 



Method of injecting the biliary ducts. The following is the method 

 by which, after numerous trials, the author succeeded in effecting 

 this object. Lukewarm water is injected into the portal vein. 

 After a time, when the liver has become fully distended, much 

 bloody water will escape from the hepatic vein, but at the same 

 time it will be remarked that bile escapes from the duct. This 



